<div class="form-group">
  <div class="btn-group">
    <button
      type="button"
      class="btn btn-xs btn-default"
      ng-model="agg.params.row"
      btn-radio="true">
      Rows
    </button>
    <button
      type="button"
      class="btn btn-xs btn-default"
      ng-model="agg.params.row"
      btn-radio="false">
      Columns
    </button>
  </div>
</div>